linux-kernel - Re: [PATCH v2 7/9] ARM: multi_v7_defconfig: Enable support for PWM Regulators

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Message-ID: <20150701123146.GK3210@x1>
Date:	Wed, 1 Jul 2015 13:31:46 +0100
From:	Lee Jones <lee.jones@...aro.org>
To:	Javier Martinez Canillas <javier@...hile0.org>
Cc:	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	kernel@...inux.com,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	Viresh Kumar <viresh.kumar@...aro.org>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Ajit Pal Singh <ajitpal.singh@...com>
Subject: Re: [PATCH v2 7/9] ARM: multi_v7_defconfig: Enable support for PWM
 Regulators

On Thu, 25 Jun 2015, Javier Martinez Canillas wrote:
> On Thu, Jun 25, 2015 at 5:02 PM, Lee Jones <lee.jones@...aro.org> wrote:
> > On Thu, 25 Jun 2015, Javier Martinez Canillas wrote:
> >> On Thu, Jun 25, 2015 at 10:42 AM, Lee Jones <lee.jones@...aro.org> wrote:
> >> > On Wed, 24 Jun 2015, Javier Martinez Canillas wrote:
> >>
> >> [...]
> >>
> >> >> > diff --git a/arch/arm/configs/multi_v7_defconfig b/arch/arm/configs/multi_v7_defconfig
> >> >> > index f632af0..6666973 100644
> >> >> > --- a/arch/arm/configs/multi_v7_defconfig
> >> >> > +++ b/arch/arm/configs/multi_v7_defconfig
> >> >> > @@ -365,6 +365,7 @@ CONFIG_REGULATOR_MAX8907=y
> >> >> >  CONFIG_REGULATOR_MAX8973=y
> >> >> >  CONFIG_REGULATOR_MAX77686=y
> >> >> >  CONFIG_REGULATOR_PALMAS=y
> >> >> > +CONFIG_REGULATOR_PWM=y
> >> >>
> >> >> The current policy is to build as much as possible as a module in
> >> >> multi_v7_defconfig. Since this is a tristate Kconfig symbol, could you
> >> >> please change it to =m ?
> >> >
> >> > I would prefer that it stays built-in.
> >> >
> >>
> >> Ok, I've no strong opinion on this. I was just mentioning what arm-soc
> >> maintainers prefer nowadays.
> >>
> >> May I ask what's the rationale for leaving this option built-in?
> >
> > My view is that multi_v7 is used for prototyping, testing and to
> > ensure all of the vendors are playing nice together.  Hopefully
> > vendors aren't actually releasing kernels built with this defconfig!
> 
> Agreed and same for the per SoC family defconfigs, vendors should ship
> kernels with a customized defconfig.

Right.

> > During testing/prototyping time; installing and messing around with
> > modules is an over-head I can do without.
> 
> Right but my question wasn't whether multi_v7 should have the options
> as built-in or as modules. That has already been decided by the
> arm-soc maintainers who want to have as much as possible as modules.
> In fact, there have been patches posted recently to change the current
> multi_v7 options from built-in to modules.

Then I need to either stop using multi_v7 or write a pre-build script
to turn it into something useful I guess.

Thanks for the heads-up.

> Instead my question was what makes this driver special to not follow
> the current convention.

There is nothing special about this particular driver to warrant that.

> I agree that there is a trade off between having options as built-in
> or modules and I believe that is why most SoC specific defconfigs have
> the opposite policy,  that is to enable everything as built-in so one
> doesn't have to mess with modules as you said.

Precisely.

> But again, I don't have a strong opinion on this. What I think though
> is that this should be documented somewhere so the options are enabled
> following a documented rule instead of just whatever fits in someone
> workflow.

News of this new convention is new to me.  As I said, this driver
isn't in any way "special".  I was merely enabling it to make it
useful to everyone, rather than only people who are currently
supporting module support in their builds.  Which as a low-level guy,
I currently have no requirement for -- it just adds time, complexity
and more things to debug.

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog
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